The usefulness of the few published reports of the prevalence of epilepsy in children in the United States is limited by restriction of the ages studied and by inclusion of single or complex febrile seizures. Only one study provides rates by broad categories of seizure type. Thus, knowledge of the frequency of specific types of seizures in children is incomplete, and rates of some sub-categories of seizures are unknown. Case definition and identification are especially important considerations when studying disorders, such as the epilepsies, which have a variety of manifestations and in which hospitalization is not a uniform occurrence. However, no studies of the potential sources of seizure cases in a United States community have been reported, and there are no data which quantitate the characteristics of cases ascertained from different sources. The proposed investigation is designed to address the following questions: 1) What are the prevalence rates of specific types of seizure disorders in children from birth through age 19 years? and 2) Do selected characteristics of seizure cases differ according to the source from which they are identified? The implications of these differences for case ascertainment in retrospective etiological studies of the epilepsies will be assessed. Active cases (as of December 31, 1983) of recurrent, afebrile seizures in children from birth through age 19 years will be identified in Oklahoma and Cleveland Counties from four general types of sources: 1) hospital records (admissions, emergency room, outpatient and speciality clinics), 2) private physicians (pediatricians, neurologists, general practitioners and family practice specialists), 3) EEG records, and 4) other (institutions, epilepsy society). Period prevalence will be computed for 1983 and point prevalence as of June 30, 1983. Selected characteristic of the children and their seizures (e.g., age, seizure type, seizure frequency) will be compared according to source of ascertainment. Identification of children with specific types of seizures in a defined population will provide a large group of cases for subsequent etiological retrospective studies.